You can get pro kolin paste online much cheaper than from the vet.
How old is your pup? Does he have mucousy stools or is he passing any blood? I assume you have tried changing his food? I have posted several times about Freddie's tummy so won't repeat it all here but just say that he has never been brilliant in the poo department (he is 5 months now), has been on chicken and rice several times, weaned back onto kibble only for his problem to re-appear. His sister has had things much worse and has been seen by the vet lots of times - hundreds of pounds spent on samples - Royal Canin sensitive wet food sorted her out overnight, apparently, but it is very expensive and stinks. Her owner is trying to get her onto Royal Canin kibble instead - seeing her next Thursday to see how things are going. Her diagnosis was purely very sensitive tummy. I have just got some Natural Instinct raw food because I am sure Freddie can't tolerate the processed nature of kibble...